The volume of data traffic between entities is increasing at such an alarming rate that methods and associated hardware supporting data communication will require fundamental changes in the near to moderate future. In particular, the existing network infrastructures supporting present day communications, including fiber optic cables, electronic switches and associated methods of implementation, must be redesigned to support new world demands.
A common solution for the present communication bottleneck is to employ higher speed hardware. However, even the advanced speed of electronic switches can not necessarily provide enough support for the increased demand. While higher speed processing hardware offers some promise for increased bandwidth, it addresses only part of the problem. Ultimately, data transfers are limited by the throughput of the slowest link in the system.
High speed routing and increased data transfer rates of information is the key to higher speed communication. Based on certain techniques used today, network communication typically involves labeling data packets at multiple levels to facilitate the flow of data between a source and destination node. Routing in these systems, therefore, requires a tremendous amount of electronic processing power because a packet of information generally must pass through and be processed by many routers before it arrives at the appropriate destination. Unfortunately, each router hop involves processing header information of each data packet to be routed in the network system, causing considerable delays in the transmission of data.
It has been suggested that optical networks provide the greatest promise for increasing communication bandwidth because there are many benefits to directing communication data via an optical channel. Based on such methods, data can be directed or multiplexed without having to unravel and process flowing data at each router or multiplexor. This greatly reduces the amount of electronic data processing, which is typically the cause of severe bottlenecks. Additionally, and perhaps almost as important, the flow of data on an optical channel is the fastest way to transmit data since the channel bandwidth is so great. However, suggested systems are typically sub-optimal due to inherent inefficiencies.
The present invention provides a method and apparatus for increasing the bandwidth of data communication by optimizing the use of resources among nodes on a core data communication network. Aspects of an existing data communication infrastructure such as a fiber optic network can be combined with inventive hardware and methods to achieve this end.
For high capacity switching, the present invention reduces the analysis of data required in packet switching and effectively establishes circuit switching through high capacity optical switches. To that end, communication with upstream and downstream circuits, generally other switch circuits, establishes flow paths for transmitting data through the optical switches.
In particular, the present invention advantageously allows for the optimization of optical data transmissions with as few intermediate opto-electrical conversions as possible. When justified, direct high speed routing of optical data signals is achieved by switching optical signals through the core network based on assigned wavelengths and established flow paths without converting the optical signals to electronic signals at an intermediate node. An alternative embodiment includes circuitry to convert an optical signal to an electrical signal, which is thereafter directed and retransmitted as an optical signal to a destination node. Slower speed traffic is routed more conventionally from a source to a destination where WDM optical signals typically undergo a series of electro-optical/opto-electrical conversions for routing at intermediate nodes before arriving at a desired destination.
Based on the core network topology, hybrid switch circuits communicate amongst each other and peripheral nodes over at least a first dedicated wavelength to establish a flow path and assign a wavelength to be used for routing optical data signals. Each hybrid switch circuit includes an optical switch for switching optical signals based on the assigned wavelength to an optical fiber in the established flow path.
Additionally, each hybrid switch circuit includes an electronic controller for monitoring traffic on the first dedicated wavelength and controlling the associated optical switch. Once a flow path is established, data is transferred on an assigned wavelength between peripheral nodes on the core network. This method and apparatus supporting the transmission of optical data is advantageous because it provides, at a reduced cost, a method of directly routing densely packed optical data signals from a source to a destination without electronic switch converter delays. In the preferred embodiment,a flow path is based on the MPLS protocol. However, ATM routing of data is also possible in an alternative embodiment.
Each hybrid switch circuit includes an electronic controller and supporting circuitry that converts optical data signals at the first dedicated wavelength to electronic signals. This data is then processed and monitored to determine whether a flow path should be established for routing WDM optical signals. Alternatively, data flows may be explicitly requested by data management systems that monitor traffic flow through the fibers. For example, a particular link may be reserved for heavy traffic expected at a certain time of the day. Further, personnel monitoring data traffic through the network optionally create policies or rules for establishing optimal traffic flows.
Messages and data destined for other hybrid switch circuits or peripheral switches are passed on to other hybrid switch circuits through interconnecting fibers over the first dedicated wavelength. Communication among elements in the core network includes a process of learning a topology of elements in the core network and associated interconnections.
In the preferred embodiment, peripheral nodes on the core network aggregate and convert data to WDM optical signals for transmission over fibers to the hybrid switch circuits in the core network, where the peripheral node includes an electronic switch that responds to communication from the core network to forward data over the established flow paths. A peripheral node aggregating data traffic bound for other nodes on the core network transmits a message to a hybrid switch circuit in the core network when there exists a need to establish a flow path for optical routing of data to a destination node. Alternatively, the electronic controller in the hybrid switch circuits monitors data traffic and generates a message to establish a high speed flow path. In one embodiment, transmitted optical data signals on a dedicated wavelength include destination tags which are monitored to determine whether an flow path should be created for high speed, direct optical data transfers.
Communication transmitted on the first dedicated wavelength is optionally transmitted on a number of dedicated wavelengths. Further, communication among elements in the core network is optionally transmitted over an electrical link interconnecting network elements. The optical switch in a hybrid switch circuit includes a network of optical multiplexors and de-multiplexors controlled by electrical signals generated by the electronic controller. Therein, the electrical signals provide setup information for routing an optical signal at a given wavelength. Low volume data traffic between nodes on the periphery of the core network is typically transferred over the first dedicated wavelength through the core network. High volume data traffic, on the other hand, is transferred over established flow paths using assigned wavelengths when it is optimal to do so, such as when a bottleneck occurs on the first dedicated wavelength. A strategic balance is constantly maintained in the core network between direct flow paths and communications over the first dedicated wavelength such that the use of communication resources in the core network are optimized.
In the preferred embodiment, routing intelligence for establishing flow paths is distributed throughout the hybrid switch circuits in the core network. Alternatively, routing intelligence for establishing flow paths is performed, at least in part, at a central routing intelligence location.
Each hybrid switch circuit includes an optical splitter disposed in selectable routing paths to support the simultaneous flow of an optical data signal to more than one destination. Additionally, each hybrid switch circuit supports a combination of flow types within the core network itself. For example, data transferred on an established flow path in the core network is optionally converted at a switch in the core network that further transmits the data over the first dedicated wavelength. Likewise, data transferred over the first dedicated wavelength among hybrid switch circuits in the core network is optionally converted in a hybrid switch circuit in the core network that further transmits the data over an established higher speed flow path. When transmitting data over multiple or changing flow paths, data transmitted over the core network is marked for coordinating a flow of related data over multiple established flow paths.
It is anticipated that data transmission failures in the core network will occur due to failed elements. These failures are detected by monitoring received data and transmitting test packets to verify optical paths. When such a failure is detected, for example, future data transfers are re-mapped to properly functioning optical routes within the core network. In the preferred embodiment, data transmission failures on existing paths resume on a pre-computed alternate flow path, providing a quick recovery from the failure.
The present invention has many advantages over the prior art. For instance, it provides a method and apparatus to support not only lower speed data transfers using electronic switches, but also higher speed data transfers using optical routers through the cooperation of elements in a core network. Based on the flexible method and apparatus discussed herein, naturally aggregated traffic at regional networks is dynamically routed at a reduced cost with higher efficiency.